The present invention generally relates to a system for feeding pressurized lubricant to bearings within a gas turbine engine bearing compartment. More particularly, in one form the present invention defines a single dual-purpose tube including a lubricant feed-in passageway and air vent-out passageway. Although the present invention was developed for use in gas turbine engines, certain applications may be outside this field.
A gas turbine engine is typical of the type of turbomachinery in which the concept described herein may be advantageously employed. A gas turbine engine conventionally includes a compressor for compressing inlet air to an increased pressure for combustion in a combustion chamber. A mixture of fuel and the increased pressure air is burned in the combustion chamber to generate a high temperature gaseous flow stream for causing rotation of turbine blades within the turbine. The turbine blades convert the energy from the high temperature gaseous flow stream into kinetic energy, which is utilized to turn a propeller, fan, or other device. Further, the high temperature gaseous flow stream may be used directly as thrust for providing motive power, such as in a turbine jet engine.
It is well known that many components within gas turbine engines rotate at extremely high speeds. The rotatable components are generally supported by bearings located within bearing compartments. Due to the forces, temperature and speeds associated with gas turbine engine components the lubrication requirements normally necessitate the use of a forced lubrication system in order to provide adequate lubricant to the bearing compartment. A pressurized lubricant is generally fed into the bearing compartment to provide lubrication and/or cooling for the bearing, scavenge lubricant is returned from the bearing compartment and recycled for further use by cooling and/or deaerating, and an air vent line is utilized to allow air and/or an air/lubricant mixture to escape from the bearing compartment.
The continued desire for increased efficiency in gas turbine engines results in higher operating temperatures proximate the bearing compartments within the gas turbine engines. Therefore, there is an increased amount of heat transferred to the lubricants in the bearing compartments which causes lubricant deterioration, and coking may result, forming coke or sludge deposits. Coking in the air vent line can lead to blockage of the air vent line and cause overpressurization of the bearing compartment.
Thus, a need remains for further contributions in this area of technology. The present inventions satisfies this need in a novel and non-obvious fashion.
In one embodiment of the present invention there is contemplated an apparatus coupled to a bearing compartment of a gas turbine engine comprising a first conduit and a second conduit. The first conduit has an inner surface and an outer surface, and the second conduit has an inner surface and an outer surface. At least a portion of the second conduit is substantially enclosed by at a portion of the first conduit such that the outer surface of the second conduit generally faces the inner surface of the first conduit. One of the first conduit and the second conduit is a lubricant feed conduit adapted for the passage of a lubricant to the bearing compartment. The other of the first conduit and the second conduit is an air vent conduit adapted for the passage of a vent air from the bearing compartment.
In another embodiment of the present invention there is contemplated a system including a gas turbine engine having a bearing housing. The system also includes a first conduit and a second conduit. The first conduit has an inner surface and an outer surface, and the second conduit has an interior surface and an exterior surface. At least a portion of the first conduit is positioned within the second conduit. The inner surface of the first conduit defines a fluid flow passageway in fluid communication with the bearing compartment and adapted to vent air from the bearing compartment. The interior surface of the second conduit defines a second fluid flow passageway in fluid communication with the bearing compartment and adapted to feed lubricant to the bearing compartment.
In another embodiment of the present invention there is contemplated a method for delivering a lubricant to a gas turbine engine bearing compartment. The method includes the acts of feeding the lubricant through a first fluid flow passageway to the bearing compartment, and flowing a vent air from the bearing compartment through a second fluid flow passageway. The second fluid flow passageway is surrounded by and in heat transfer association with the first fluid flow passageway.
One object of the present invention is to provide a design that cools the vented air with the pressurized oil feed.
Further forms, objects, features, aspects, benefits, advantages and embodiments of the present invention shall become apparent from the detailed description and drawings provided herewith.